(19)
(11) EP 0 263 644 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
22.02.1989 Bulletin 1989/08

(43) Date of publication A2:
13.04.1988 Bulletin 1988/15

(21) Application number: 87308701.9

(22) Date of filing: 01.10.1987
(51) International Patent Classification (IPC)4: E21B 44/00
(84) Designated Contracting States:
DE FR GB IT NL

(30) Priority: 07.10.1986 US 916268

(71) Applicant: Anadrill International SA
Panama City (PA)

(72) Inventors:
  • Sheppard, Michael C.
    Shudy Camps Cambridge (GB)
  • Wick, Christian
    N-5061 Kokstad Bergen (NO)

(74) Representative: Dupont, Henri 
c/o Schlumberger Cambridge Research Limited Post Box 153
Cambridge CB3 0HG
Cambridge CB3 0HG (GB)


(56) References cited: : 
   
       


    (54) Method for investigating drag and torque loss in the drilling process


    (57) Drilling conditions are analyzed by, for example, measuring the torque (37) applied at the surface to the drill string (11) and the effective torque (20) acting on the drill bit (14). The applied torque and effective torque are compared to determine torque loss. Likewise, applied weight on the drill string and effective weight acting on the drill bit may be measured and compared to determine drag losses. These measurements and comparisons may be done in real-time to diagnose unfavorable drilling conditions. The torque or weight measurements may be used to calculate a variable coefficient of friction acting on the drilling string. Trends in the torque or weight losses, or in the value of the coefficient of friction, may be observed on a plot of these quantities as a function of depth.







    Search report